The membership certificate of the Zenglong Kongsi, a Hokkien secret society in Singapore that can be traced back to the Tiandihui (Heaven and Earth Society), has the eight-sided diagram (bagua) incorporated into it. The bagua holds special significance in Taoist tradition, which yields considerable influence over the beliefs of the secret societies. Such certificates had to be carried around by members at all times for identification purposes. The name of the society is printed on top of the certificate, which also carries the necessary stamps for its validation. The local version of the Tiandihui originated from the secret society in China, a sworn fraternity comprising Chinese men with the common aim of overthrowing the Qing dynasty and restoring the Ming. With increased Chinese migration to Singapore, the local society became a form of mutual-aid and support, and various splinter groups (hui or kongsi) subsequently emerged among the main dialect groups.
